


Just Keep Swimming

by littleblackfox, NurseDarry



Category: Captain America (Movies), Marvel Cinematic Universe
Genre: Body Modification, Gen, M/M, Wait come back!, a ridiculous amount of whimsy, mild PTSD, non-graphic shark attack, post-Winter Soldier future AU, slightly ambiguous ending, truly horrible jokes, world-ending peril
Language: English
Status: Completed
Published: 2018-05-19
Updated: 2018-05-19
Packaged: 2019-05-08 07:48:00
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 11,705
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14689649
Author URL: https://archiveofourown.org/users/littleblackfox/pseuds/littleblackfox, https://archiveofourown.org/users/NurseDarry/pseuds/NurseDarry
Summary: High seas shenanigans with pirates, nuclear bombs, recurring villains, and SCIENCE. Then things take a decidedly fishy turn. Also, Steve’s “list” grows to about the size of a blue whale. You’re gonna need a bigger Helicarrier.





	Just Keep Swimming

**Author's Note:**

> NurseDarry:  
> Of course, this would be nothing - less than nothing - were it not for my super-patient, super-supportive, super-talented, and super-duper artist, [Littleblackfox](http://thelittleblackfox.tumblr.com/). Thank you for being my inspiration and my friend through these interesting few weeks full of crap skip suppliers and surprise relatives. You helped shape this fic with your great ideas, and helped me hammer(head) it out into a work I'm very proud of. I could not have done this without you.
> 
> I suppose the CapRBB moderators should get a mention in here too: you're my favourite leaders, and I won't be at all surprised when you take over the world. Thank you for once again giving us this opportunity to create and have fun. Xx
> 
> Special thanks also should go to my long-suffering beta [DelphiPSmith](https://archiveofourown.org/users/DelphiPsmith), with oodles of help from [Xantissa](https://archiveofourown.org/users/Xantissa), [April](https://archiveofourown.org/users/sparkly_butthole), [Chiyume](https://archiveofourown.org/users/Chiyume), [Cleo](https://archiveofourown.org/users/cleo4u2), and my posse on WhatsApp. Thank you also to [Opposablethumbs](https://archiveofourown.org/users/opposablethumbs), who helped me make it through Infinity War (twice), as well as providing sustenance and kitten therapy. And finally, to David Attenborough, who forced me to write this.
> 
> Littleblackfox:  
> A thousand thank yous to Darry, for taking an outlandish prompt and running with it!

**Part One**

**__** _Mayday, mayday, this is the cargo vessel Ongwe. We are under attack by unknown assailant. Position seventeen degrees north by one hundred and four degrees west. Repeat, under attack by unknown assail -_

The message was repeated in Morse and by voice, until the bright dot on the radar screen slowly faded, then disappeared completely. 

<>< <>< <><

Bucky and the rest of the team looked on as Nick Fury stood before the rotating holographic map displayed in one of the Helicarrier’s situation rooms. Outside the cloaked windows of the giant vessel, the Greek islands appeared to bob up and down with the gentle motion of the Mediterranean waves.

“So that's the situation," Fury concluded. "Sinkings, hijackings, and piracy in the North Atlantic, deliberate destruction along the Great Barrier Reef, and attacks on two Antarctic research stations.”

Bucky side-eyed Steve, who spoke up. “You sure it’s not some project run by the government? Or even S.H.I.E.L.D?”

“Capsicle is right,” Stark added less-than-helpfully. “How do we know that it’s not one of yours? Don’t forget, you were the bad guys not too long ago.” His gaze slid over to Bucky’s with blink-and-you-miss-it meaning before focusing once again on Fury. And Hill, by Fury’s side.

“It’s not us,” Fury assured him. “S.H.I.E.L.D. has been completely re-organized -”

“Rebranded, you mean.”

“Stark,” Steve said, the warning tone barely masked.

“And this isn’t S.H.I.E.L.D.’s first rodeo with these guys.” Fury nodded towards Simmons. “Agent Simmons and Dr. Cho have been working to determine if these raids are being carried out by organics, robots, or even alien agents. No news on that front, but the Asgardians assure us it’s none of their doing.”

“What exactly are we talking about, then?” Steve was quick to cut into what was slowly becoming one of Fury’s overly-dramatic exposés. “Is this -?”

Hill said, “It’s the same group of… pirates - for lack of a better word - that the Avengers have also recently engaged on recent missions. Remember the ferry sinking in Scandinavia and the earthquake in Queensland? We just didn’t know that at the time. Aside from all the piracy, there’s the geological consequences that follow the destruction of natural resources - we’ve found evidence of underground avalanches, and other mysterious disturbances in the environment that haven’t yet affected the human population.”

“Can’t understand how we keep missing them with all the cutlasses and eye-patches.”

“Stark,” Steve and Fury both growled. Stark rolled his eyes but shut up.

“Up until now," Fury and his own eyepatch continued, "the kinds of things being stolen are what you’d expect from many modern-day pirates: heavy equipment, computer components, rocket fuel.”

“The usual D.I.Y. scary regime stuff,” Barton added his two cents.

Fury nodded. “And so far, there hasn’t been enough of it taken to get particularly worried. We sent you all out when there were human casualties to consider, but we never focussed on their endgame. At least not until now.”

“If this is being perpetrated by a hostile country, or even mercenaries, I’d say that’s enough to be worried about,” Romanoff pointed out soberly, earning herself a silent nod of agreement from Steve.

“The problem is, there’s no pattern, and not much has actually been stolen. Often most of the cargo is just dumped into the sea or abandoned.” Simmons spoke up. 

Wilson let out a low snort. “Sounds like someone’s made a good start on a school project.” 

“Until now,” Fury informed them. “All one hundred tons of a shipment bound for the Bay Area was recently intercepted and forcibly removed from a Namibian-registered cargo ship just off the west coast of Mexico.”

“Shipment of what?” Steve asked slowly.

“The manifest says everything from farming equipment to toilet seats.”

“Which actually means?” Steve prompted, and Fury’s jaw clenched.

“Wakandan vibranium,” he said. “Bound for the science and outreach centers being built in Oakland by King T’challa.”

“So whoever -”

“Or whatever,” Stark interjected smoothly.

“...or _whatever_ this pirate is, he now has computer components, rocket fuel, heavy machinery, _and_ vibranium?” Steve ended, with a pointed arch of his eyebrows.

“And toilet seats,” Barton reminded them.

“Yes, I think we can assume those were part of the phony manifest,” Fury clarified.

“C’mon, everyone needs toilet seats,” Barton argued.

“True that,” Wilson agreed.

“People, the point is,” Hill cut in, “that this has now not only become an international political incident, it’s also become an international safety imperative. We need to find whoever this is and stop them. Anyone with that kind of stealth and shopping list can’t be planning anything beneficial for humankind, or any other kind, for that matter.”

“So what have we got?” Steve asked. “Can we track them somehow?”

“Drs. Banner and Selvig have been working on a way of identifying and tracking whatever means these pirates have to travel and engage with these cargo ships.” Fury confirmed. “It’s similar to the system developed for identifying the Tesseract.”

“Does this mean we’re talking Hydra, or some other powerful organisation?” Steve asked.

“The lack of attacks on land would indicate that whoever it is has an offshore base of some kind,” Hill clarified, which didn’t really answer the question.

Bucky shifted in his seat, looking at the map displayed on the holoscreen in front of them with a contemplative frown. “Could there be some _undersea_ base somewhere?”

“How very James Bond,” Stark quipped, obviously amused by the idea. Bucky could almost see the wheels going round in his head.

“Which has a fleet of pirate ships at its disposal,” Romanoff added, although in a less teasing tone.

“Not an entire fleet, but maybe on a smaller scale than that,” Steve said, leaning forward in his seat. “What about subs?”

Hill shook her head. “We thought of that, but there’s been nothing from SOSUS or any other network of early-warning systems. And assuming they were the ones who hijacked all the ships that have reported losses, there’d need to be a network of them - S.H.I.E.L.D. teams have been chasing these guys from the Arctic to the South Pacific. Nothing has been documented coming through any of the canals, and no one has reported seeing anything.”

“How about just one very fast ship?” Banner asked.

Hill shook her head. “Fast enough to get from the eastern Med to the west coast of Panama in two days? Because that’s what’s just happened. There’ve been no reports of anything moving that fast through the Straits of Gibraltar, and nothing that can’t be traced going through the Panama Canal. Whoever it is, they’re taking the long way round. Or there’s more than one of them.”

“So what do we do now?” Clint asked.

“Hurry up and wait,” Stark said, ever-helpful.

“Well…” Banner hesitated while making eye contact with Selvig. “We have actually found something near the Bahamas that might be what we’re looking for. The water is shallower there, but there’s no way to get any kind of direct surveillance, either via GPS or sonar. It’s almost like something’s blocking us -”

“Or it’s a big alien,” said Stark.

“Or a sea monster,” said Barton. 

“Maybe both?” Thor interjected.

Fury growled, “Not helping.”

“How long ago was the last hijacking?” Steve asked.

Hill consulted the display and looked up. “Thirty-six hours.” 

Steve frowned. “So this thing got from the west coast of Mexico to the Caribbean in thirty-six hours without going through the Panama Canal?”

“Or there’s more than one of them,” Romanoff reminded them.

Clint shifted around, as eager as Bucky to stop with the lecture and get on with the action. “So what’s the plan?”

“Recon for now, until we know what we’re dealing with. But let’s not let this fish slip away.”

“Time to suit up,” Steve said with his Captain America voice.

“You mean swimsuit up!” Barton joked. Badly.

Fury called for wheels up, figuratively speaking, and no one responded as they left the conference room. 

<>< <>< <><

In a S.H.I.E.L.D.-made sleek, low-profile yacht, Hill bent over the sonar equipment and scanned the depths. Bucky was impressed with the craft’s design; it blended in well with the other expensive-looking vessels scattered around the Caribbean. They would easily be mistaken for just another billionaire showing off. Which one of their number actually was. Above them, the cloaked Helicarrier hovered at 30,000 feet, and comms lines were open to include any information needed from the team there.

Stark, however, was below, scanning the sea beneath them for the signal Banner and Selvig had detected and narrowed down to this area. 

“So there’s some black-and-white stripy fish -” Stark’s tinny voice wafted through the comms.

“Yeah, Stark, that’s not what I meant when I asked if you’d seen anything. I meant anything _suspicious_. You’re outside of camera range now.” Hill sounded exasperated. Which was almost everyone’s default emotion when dealing with Stark.

“ - ooh, and some bright yellow ones. Wait, would a big scary shadow count as _suspicious_? Because there’s a big scary shadow ahead. It’s actually getting bigger and scarier as we speak. Can you scan it, guys? Is this thing alive?”

“It’s not organic,” Cho verified from above.

“It’s scary, though, right?” 

Simmons confirmed, “Yes, uh… scary. And big. It’s big, whatever it is.”

Selvig turned from his monitor, which still glowed and pulsed with unearthly luminescence. “I can confirm the readings are coming from whatever that tha ---”

An enormous pressure-changing pulse and huge **BANG** had everyone reeling. Banner and Selvig ripped off their headphones, and the boat lurched sickeningly. Foamy water broke over the port side, and everyone shouted and cursed as they tried to regain their footing. Bucky yawned, trying to pop his ears, his hearing as unbalanced as his feet in that instant. 

“Stark!” Hill shouted, righting herself while still managing to keep a careful eye on sonar now that Stark could no longer be seen in the powerful underwater cameras. “Report.”

“Uh… guys?” Stark’s shouted through the comms. “Guys, power’s out, JARVIS isn’t responding, I can’t hear shit, and I’m dead in the water, so, you know, typical day. Don’t suppose anyone would like to come and get me before I sink to the bot-- oh wait, too late.”

“Stark, hang on, we’re sending out Romanoff and Barnes now. They’ll bring you some juice for the suit.”

“Whoever’s speaking sounds like Charlie Brown’s teacher, so I’m just gonna hang here in the sand with the flounder. I’m assuming someone’s coming to me, since I’m not going anywhere.”

“That thing released some kind of electronic depth charge,” Selvig reported. “Our equipment appears intact.”

“Even if our eardrums might not be,” Barton said with an exaggerated yawn and shake of his head.

Steve looked askance. “Correct me if I’m wrong, but isn’t that kind of thing usually used by ships to destroy subs, and not the other way around?” He looked over at Bucky for confirmation, who nodded.

“Are we even sure that thing is a sub?” Romanoff asked, bending down next to Hill to peer at the sonar equipment.

Singing now sounded through the comms. “I’d like to be, under the sea, in an octopus’s -”

“STARK!” Hill cut in, “if you can hear me, you need to shut up.”

“Heyyyyy,” Stark said, “I think my ears are getting better; I can hear Hill shouting at me.”

“Romanoff, Barnes, get out there and bring him back.” 

Bucky and Romanoff finished prepping their scuba equipment and slid into the water, which was still agitated from the electrical disturbance. 

Bucky ignored the myriad of interesting things swimming around him, and focused on Romanoff’s bubbles as she homed in on Stark. 

Dropping the watertight battery pack on Stark as they swam by (it made a satisfying "thunk" as it struck his helmet), Romanoff and Bucky carried on as stealthily as possible toward the looming shadow in the depths ahead. Unfortunately, "as stealthily as possible" wasn’t really stealthy at all, as there was no cover, just sand, a few outcroppings of coral, and colorful fish in the mostly-clear water where they swam. 

They exchanged hand signals, silently agreeing that in order to see what this thing was, they’d have to go deeper. They continued cautiously, but what should have become clearer the further down they went, didn’t. It was as though something was emanating from the… thing, something that obscured their focus; a forcefield or camouflage of sorts. Their suit cameras should have been on, relaying what they saw back to the team, but when Bucky checked the little LED indicator he saw that his wasn’t functioning.

Suddenly, through the quiet depths came a booming, chilling, and very distinct voice.

 _That’s far enough, I think_. The accent and cadence were eerily familiar.

“My god,” Bucky heard Steve breathe through the comms. “It’s Zola.”

Bucky and Romanoff pulled up, windmilling their limbs and halting their forward momentum as much as possible. The water between them and the object suddenly cleared, and they saw... well, it was mostly submarine-shaped. But that’s where the similarity ended. The thing was enormous; easily half the size of a Helicarrier. The hull was indeed long and cylindrical, but it was much wider, and sheathed in a hazy blue aura, with multiple spikes of varying lengths and sizes jutting from it in all directions. Bucky could see no conning tower, and there didn’t seem to be any screws - in fact no visible propulsion system at all.

_Correct, Captain Rogers. It is indeed I, again returned from the dead. Which is how I thought I had left you. Sadly, I see that I was incorrect in that assumption._

Bucky struggled to keep his breathing even, but hearing that voice again, it was all he could do not to scream into his regulator.

“You mean _the_ Zola?” he heard Simmons ask. “How can he still be alive?” 

Fury's voice spoke from above. “Zola incorporated his... mind into a computer system, which we assumed had been destroyed during Project Insight. It appears we assumed wrong.” It was an echo of Zola’s admission of his error over Steve’s death.

Unaware he was doing so, Bucky shook his head violently back and forth, overcome by anxiety. This could not be happening. How had he escaped this maniac only to literally stumble upon him again?

 _As you can see, I am completely restored. I would never have sacrificed myself for something as inconsequential as_ your _death, Captain. Where do you think the missile that destroyed Lehigh came from? It came from this vessel. Pierce never knew it existed, and thought I’d been destroyed in the blast. I always knew Hydra could be taken down again, and I have been accumulating a small army and an arsenal ever since. What Insight failed to do, I will do ten times over._

“Monologuing…” Stark sing-songed sardonically from behind them.

Bucky’s entire body was shaking now. Static filled his ears, and he heard nothing but white noise. Romanoff turned her masked face in his direction, no doubt assessing his mental state and formulating a plan. But he had no time for her worry now. He didn’t care what the plan might have been. Seventy years of pain and anguish flooded through him... and anger. So much resolve. Whatever the current circumstances, he was not going to let Zola hurt him again. Not him, or Steve, or his new team. He kicked his powerful legs and zoomed towards the sub.

“Barnes!” Stark and Romanoff shouted.

“Bucky!” He heard Steve’s cry, but then the rage blocked out everything else but his blind urge to increase his forward momentum. He had no plan, no idea how he’d get into the vessel, but he’d claw away at it until he had Zola’s throat in his grip, however he could achieve that.

So focussed on his attack, Bucky failed to notice the radical change in pressure and temperature around him, as well as uncanny yellow glow about his body, but he _did_ notice the change in his speed. Suddenly he was shooting through the water like a rocket; in what seemed like seconds he was at the sub, and he went for the first thing he could get his hands on in an attempt to gain access. Except... he couldn’t feel his hands anymore. He couldn’t _see_ his hands anymore. And when he pulled up in an effort to stop himself, his face met metal. He bumped against it and rebounded back.

“What the…” he heard Romanoff say. “Barnes, can you hear me?”

“Zola’s mine, Romanoff, stay away!” Bucky shouted into his… wait. There was no regulator, no mask, no wetsuit constricting him. There was just... water, pressing against his skin.

“Grab that gun, Barnes! And get out of there!” 

_Gun? What gun?_ Bucky looked around, and spotted a large metal appendage attached to the ship, which he’d encountered when he’d rammed into it. Rage seized him again.

“I want him dead!” Bucky shouted. He yanked at the canon-shaped thing, crushing its moorings, chomping at it until it came loose in his… mouth? 

He had it in his mouth! He’d pulled it off the sub with his teeth! What the hell had happened to him?

“Swim, Barnes! Get back to the base! NOW!” Hill shouted. 

Bucky wasn’t so easily deterred. His mouth full of metal, he rammed the sub again with his nose.

“Bucky, fall back to Nat’s position and get the hell out of there!” Steve’s voice sounded frantic, and it was that note of panic that finally cut through Bucky's fury and stayed any further attack. He turned and made his way back to Romanoff in no time, still holding the strange-shaped metal appendage.

“I need you to calm down, Barnes,” Romanoff said gently as she treaded water in front of him. “I need you not to panic.” Her eyes were wide, and it was clear she was trying to keep her own panic at bay. “And I need you to be careful. Don’t break that thing.”

“What the hell is going on?” Bucky said with his mouth full.

“That thing you’ve got is some kind of weapon,” Stark said, now hovering beside her. “And it… changedyouintoashark. There, I said it.”

“WHAT?!” shouted Steve and Bucky at the same time. 

“He’s right, you’re a… shark,” Romanoff confirmed. “And now we’ve got to get you back to base before Zola tries anything else. Come on.”

“But -” He tried to frown but his forehead felt...wrong. And somehow he was making himself understood without using his mouth.

“Buck, we’ll get him, I promise, but you need to get back here now. If you’ve been injured -” Steve pleaded from the boat.

“Cap, did you not hear what I just said?” Stark said. "I don't think _injured_ quite covers it."

Bucky looked at Romanoff and Stark, and then angled upwards towards the boat. As he reached the hull, he spun around as fast as he could to see what had become of his body. All he saw was a large tail. A tail that _did_ look remarkably like it could be a shark’s. 

He carefully held onto the weapon in his mouth while thrashing about, looking from different angles and trying not to panic, but hardly believing his eyes. 

“Come on, Buck. I don’t know what Stark’s talking about, but you need to get back here.”

“I _am_ back, and I’ve got the weapon,” Bucky complained. Nobody seemed to appreciate his achievement. 

“Be careful. Try not to touch it too much.” 

“It’s in my goddamned mouth, Steve, I _am_ touching it too much.” He wondered again how the hell they were understanding him.

Fury’s voice-over cut them all off. “Hill, get everyone back on board and get the hell out of there. We’ll head back to sea and rendezvous with you at… sending the coordinates now.”

It was a good strategy not to disclose the position over their shared channel, just in case Zola could intercept their comms, despite Stark’s claim that with the sophisticated equipment on the boat, it was impossible. It was impossible to turn a human being into a shark, too. Or at least Bucky had thought so. But some strange shit had happened to all of them, so Bucky wasn’t as surprised as he could have been, he supposed. 

Didn’t stop him from being pissed off about it, although Steve’s face on seeing him helped a little at least.

<>< <>< <><

By the time the team arrived back at the Helicarrier, Banner and Cho had ensured a tank filled with seawater had been erected in one of the cargo bays. As soon as the divers and the speedboat had rendezvoused with it, the Helicarrier had risen back up to the sky, taking the boat and the team with it.

Now Bucky swam around in grumpy circles, alternately looking through the glass at everyone as he passed by them, and staring at himself in a mirrored panel mounted at one end of the tank. 

The Winter Soldier had become the Winter Shark: there was nothing left of the human Bucky Barnes aside from his coloring, and most probably his attitude. He was still decked out in black, although he noted his bottom half was white, a color he rarely wore aside from his boxers. 

His left pectoral fin was silver with the red star he loved to hate adorning the top. Bucky pressed the fin against the side of the tank and was surprised to see that it bent against the glass. So it wasn’t metal. But then what the hell was it? It certainly felt different from the other pectoral fin. 

He pointed his snout at the mirror and inspected his sharky face with its eyes that seemed more at home on one of his sisters’ scarrier-looking dolls, and frankly, more teeth than any creature needed. 

Bucky wondered what Steve thought about all of this, and hoped like hell someone could fix it. And soon. 

The debrief was less conventional than previous ones, as the team had to assemble next to the tank to include him in it.

“Where’s Fury?” Stark asked

“Busy,” Hill said curtly. “I’m leading the debrief. He’ll join us later remotely.” 

“Is he even on board?” Stark had disposed of his suit and was pacing about, hands never still, probably looking for a coffee maker or juicer, or screwdriver. He ambled over to the side of the large cargo bay where Cho was inspecting the dented weapon Bucky had returned with. “Don’t tell me he gets seasick.”

“No,” said Simmons. “He’s okay with the water.” Bucky and Steve might have been the only two who heard the “thankfully” she added under her breath. Bucky wondered what that was all about.

“Listen up,” Hill drew their attention back to the debrief. “We need to know what the hell just happened.” She made a passing gesture at the tank and its finny resident. But we also need to figure out how we’re going to take out Zola and that sub. It’s clear this is bigger than just piracy. This is Hydra we’re talking about.”

Bucky picked up speed in his tank, swimming agitatedly in tighter circles until Steve absently placed a hand against the glass. Chances were Steve wasn’t even aware he was doing it, but Bucky was grateful for the connection, as impersonal as it was. He gently bumped his sensitive nose against the glass and the rhythm of Steve’s heartbeat steadied him.

Hill continued, “So I want two teams - Simmons, Cho, Stark, you’re in charge of analyzing this weapon and finding a way to reverse it.” She looked up at the tank, and everyone followed her gaze. “We need Barnes back, and anyone else who could be affected by it in the future.”

“On it.” Stark had already started tinkering with the weapon and didn’t look up. Cho and Simmons both nodded.

“Banner, I need you and Selvig to come up with a way to knock out that sub. Zola’s already got enough on board to take over a small country -”

“Uh, yeah, about that?” Stark’s comment drew all their attention. He held up a palm-sized piece of equipment that emitted a blue light. He ran it over the weapon, then turned to the tank. “Barnes, hold still a moment; yeah, I know, you gotta swim to breathe…” Stark passed the thing in his hand across the glass in front of Bucky and checked the readout. “Zola may not be looking to just take over a small country, he may be looking to blow up a big one. Or all of them, actually.”

“Stark, English,” Hill said.

Stark finally made eye-contact with the team. 

“Both the weapon and Barnes are emitting a radiation signature. Zola’s got some kind of nuclear fuel on that sub.”

“What kind of radiation signature? Is it dangerous?” Steve looked anxiously from Stark to Bucky, and back to Stark again.

“Not enough to make your boy glow in the dark or anything, Cap. Just enough to know that both of them have been near something with a powerful radioactive influence." 

Despite Stark's reassuring tone, Bucky didn't feel particularly reassured. But, whatever the emitter had detected, it didn’t seem to have made Cho or Simmons unduly concerned, so Bucky let it go for the moment to concentrate on the bigger picture. Zola had nuclear fuel, and clearly a means of designing weapons. Weird ones, if his present shape was anything to go by. They’d have to act soon.

Cho regarded the computer equipment she’d set up in the makeshift lab next to the tank, leaving Tony to the hands-on work. “There _is_ some good news. I should be able to reverse the beam on this - but it’s going to take a little time.” 

“How long is a little?” Bucky asked, just as Steve opened his mouth, probably to ask the same thing.

“Well, if Simmons can assist me, maybe two to three hours. I think we can untangle your own DNA from what you’re currently swimming around with.” 

Cho sounded competent, and Bucky wanted to believe her.

“How is it you can hear me?” Bucky asked.

Simmons spoke up, “It’s actually rather an interesting phenomenon, and one I’ve been looking into. It’s not strictly scientific. It’s actually more…” She stalled, clearly considering how to phrase the explanation in order for them to all understand it.

“Alien tech,” Banner said succinctly, looking over at the tank. “Humans only communicate on a conscious level, but other species are capable of multiple levels of contact. Thor, for instance, is able to communicate with other Asgardians subconsciously. Or at least some of them. He summons his hammer the same way.”

“So Hydra has harnessed this,” Steve said. It wasn’t a question.

“Mostly likely it was part of what they unlocked with the Tesseract,” Selvig explained. He and Barton exchanged a quick look, and Steve glanced over at both of them a little suspiciously. “But that's only a guess. It’s not something I was part of,” Selvig admitted.

Steve turned back to the tank. “They’ll figure it out, Buck,” he said, patting the glass, and Bucky could feel the warmth and reassurance flowing towards him.

If it were possible, Hill became even more businesslike. “Let’s get to work, people. Fury and I will keep monitoring the sub as long as we can, and work on a way to make sure we don’t lose sight of it again. Romanoff, Barton, we need you to come up with a plan to get closer to it. Clearly what we tried today isn’t going to work. Unless Selvig and Banner can come up with a way of destroying it remotely, we'll need to get past its defenses.”

“When do we ever get to do that?” Clint grumbled. “That’d be way too easy.”

“We’ll reconvene in twelve hours.” 

A hologram of Fury’s top half appeared in front of them, superimposed over the tank, facing the rest of the group. “Captain, I assume there’s no point in asking you to leave here to work with Romanoff and Barton.”

“You assume correctly,” Steve said in that steadfast way of his. Bucky bumped his nose against the glass under Steve’s hand. “Sam can give them whatever help they need.”

Wilson nodded, and the hologram disappeared as quickly as it had appeared. 

Bucky wondered if Fury had thought his presence along with Hill’s would coerce Steve into leaving. _Should have known better_ , he thought, shaking his head and sending a sploosh of water over the side of the tank.

The team broke up as the various members made their way around the bay to their work stations or out of the area completely. 

“Nice of the chief to drop in,” Barton said sarcastically about Fury’s flying visit.

“You’re lucky he stuck around _that_ long,” Bucky heard Hill say as they walked out together. “He hates sharks.”

Bucky, showing all his teeth, grinned.

<>< <>< <><

“Will we just test this on him or on something else first?” Simmons asked two hours later as Cho made another adjustment to the weapon. It lay housed in a metal casing in the bay and was pointed directly at the tank. 

Bucky hung in the water on the other side of the glass, tail gently swishing to and fro. He’d answered questions for what felt like forever; he was grateful to Steve, who'd tried to keep up his spirits with stories from the old days. Good ole Steve.

Steve moved to stand between Bucky and the three scientists. “You can test it on me,” he said firmly. Yup, _same_ good ole Steve. 

“Heh, I knew I left all the stupid with you,” Bucky teased, bubbles rising in amusement.

“Cap, as predictably chivalrous as that is, it’s hardly helpful. We’re working to turn Mr. Loverboy back into Robocop, not to turn you into Jaws.” 

Steve scowled. “That’s some other cultural reference I don’t get, isn’t it?”

“Just do it,” Bucky said, pre-empting any more discussion about Steve’s altruistic behavior or late 20th century cinema.

Tony swivelled around in his chair. “Hold your seahorses, Barnes, we need to make sure this isn’t going to turn you into a mermaid or something.”

“Are you sure he’s even okay like this? That’s it’s not… hurting him somehow? How do we even know it can be reversed?” Steve asked.

“He’s fine,” Stark assured. “He’s breathing like a shark, swimming like a shark, talking like a - wait, hold on… Nope, not sure of anything, Cap, but I’m sure he’d tell you if he wasn’t. Guy has a way of doing that, if I recall.”

“Tony…” Steve warned, and even through the glass Bucky could tell that his patience with Stark's nonsense was wearing thin.

Stark carried on, all the while still pressing buttons and twisting knobs. “Not hungry or… anything? Someone’s bound to have a couple cans of tuna or a license plate lying around we could toss in there.”

“Dammit, Stark,” Bucky growled, baring his impressive array of teeth. If only he could get out of the tank for a second... “Just hurry up. I don’t want to end up swimming around Sheepshead Bay the rest of my life.” He turned and angrily swam to the far end of the tank. He waggled his left fin at the mirror as he passed, wondering, as he often had over the last few years, how he’d ended up here from where he’d started.

“We’ll get you back on your feet soon… your _real_ feet,” he heard Simmons say. 

Bucky had to admit she had a much better tank-side manner than Stark. 

“It’s actually not that sophisticated,” Cho said, sounding just a little bit smug. “I think they were experimenting with some kind of matter-transfer device, but ended up creating a gene splicer instead. Luckily for you, Sergeant, that’s my area of expertise. Simple as it is, this bit is actually quite clever; for a start, your fin is flesh, but has metal, rather than cartilage supporting it, giving it both the color and added strength. Don’t ask me how you’re maintaining buoyancy with it, though; I’d need a more detailed molecular scan of the metal to determine that. The star pattern on it is made of your shark-skin cells, rather than having been painted on or in any other way artificially _designed_. It’s as though the metal is actually _part of you_.” 

Bucky glided back to the front of the tank, where he looked first at Steve and then at the three scientists. “What does that mean, exactly?”

“Mean’s underneath all that hair and grumpy-cat exterior, you really _are_ a lean, mean, fighting machine,” Stark said. 

“It means,” said Simmons, anticipating the usual response to Tony’s explanations about anything, "that you’re still you underneath that shape and we can get you back into your own without too much trouble. This weapon, or whatever it is, might have been designed to fend off attack by rendering the attacker powerless.”

“A shark isn’t exactly _not_ dangerous,” Steve pointed out.

“No, but it’s less dangerous than the world’s most famous and scruffiest assassin packed to the gills - see what I did there? - with guns and explosives."

Bucky rolled his shark eyes to full effect. Stark didn’t look the least put out, but before he could say anything, Hill’s voice sounded across the bay from the comm unit mounted on the worktop. “We've intercepted a message which Zola's sent to all major world leaders. He’s threatening the planet with nuclear war, and is simultaneously targeting Washington D.C., London, Buenos Aires, Beijing, and Wakanda for the first strike in four hours’ time. It looks like he’s making good on his claim about picking up where Insight left off, and we can’t afford to let him get away. Currently, the sub’s travelling south at speed; ETA Cape Horn in thirty minutes. The plan is to intercept when he reaches the south Pacific, which Dr. Selvig thinks might be his final destination in order to avoid the worst of the blasts.” 

Everyone looked at everyone else, then Cho calmly said, “Okay, Sergeant, we’re ready...” 

**Part Two**

The Helicarrier cleared the airspace over the west coast of Costa Rica on an intercept path with the sub. The team - including Bucky, after much thrashing of limbs and fins, and a ting of embarrassment at finding himself returned to human form wearing only white boxers and treading water - gathered on the bridge. The Pacific Ocean filled the carrier’s viewscreen.

Banner, looking more rumpled than usual, laid his palms on the table. “If Zola’s using Tesseract technology, we can’t just go barrelling in again. And if he’s got nuclear weapons, the world’s in even bigger trouble. Enhanced with vibranium, there’s no telling their range or destructive power.” 

“Like I said, I suppose it’s too much to hope for Thor just lighting up his ass from here,” Clint said regretfully.

“Yes, it is. There’s an intricate network of sensors around the sub, that’s how he caught us,” Hill said. She looked to Selvig.

Selvig explained, “Chances are he saw you coming from further out, but waited until you were at your most vulnerable before revealing himself. The vibranium may be enhancing the range too, maybe not. I’m not familiar enough with its properties.”

“And of course there’s a nuclear component to his activities now,” Fury reminded them. “Vibranium-enhanced weapons are not something we want to tangle with. If he launched something like that while we were miles out, we’d have the sub _and_ the weapon’s targets to deal with. We’re good, but we’re not that good.”

“Speak for yourself,” Barton said cheekily.

“May I make a suggestion?” Simmons asked quietly. Everyone turned to look at her, and she turned pink. “Why not use this… this… fish-ray thing to your advantage ? We know how it works, _and_ now we know how to reverse it. You could easily sneak up on that sub if you were… actual fish.”

The room became unusually quiet. Steve broke the thoughtful silence. “I suppose we could take out the crew more easily as sharks. But we’d still need to get the weapons off the sub.”

“Actually, Captain, you wouldn’t all be sharks," Cho said. "The apparatus doesn’t work that way.” 

“Oh?” Stark sat up straighter in his chair. “And you didn’t share this information with the rest of the class?”

Simmons squirmed a little in her seat, and went even more pink. “Dr. Cho and I… had a go with it ourselves, after we changed Sergeant Barnes back into human form. Neither one of us turned into a shark.”

Clint asked what everyone was thinking. “What did you turn into?”

“I became a starfish,” Cho said.

Simmons said, “I was a turtle.”

Banner, ever the scientist said, “That’s...really interesting. Did you repeat the experiment? And if so, did you turn into something else the next time?”

“Yes,” Cho said. “And no, we became the same things the second time. While we were finding a way to reverse its effects, we’d hypothesized that the device works as a function of DNA. So your human DNA determines your piscine equivalent.”

As one, the team looked at Bucky, who shrugged. Then everyone started talking at once.

Stark’s voice cut across the group’s collective noise. “How cool is that?! Like a Patronus.”

“Hey, that’s one I know!” blurted Steve.

Thor frowned. “So I would become some Midgardian sea creature?”

“As Zola presumably only had terran DNA to refer to, it’s unlikely this thing recognizes anything... otherworldly. But there’s no telling until you’ve been exposed to it,” Cho explained.

“I concur with Dr. Simmons," Selvig said. "I think using this to our advantage is the best way to get close enough to disarm or remove those warheads. We’ve enhanced our detection technology so we’ve got a better idea where the sub is. But the tricky bit is getting close enough to do anything.”

“Drs. Banner and Selvig have recommended getting no closer than five kilometers out. We were only about five hundred meters away last time, so we can assume Zola knew we were there from the start.”

“But Zola will know how this thing works. He might be expecting... fish,” Romanoff pointed out.

“He might be expecting a shark with a metal fin,” Cho countered, "but I’d bet he can’t scrutinize all the sea life around him to the degree he’d need to discover whether it was genuine. The only way of telling the difference between a real shark and Sergeant Barnes, aside from the modified fin, would be through tissue sampling.”

Hill reasoned, “As long as we camouflage Barnes’ fin, and make sure comms are secure, this could work.” She sounded confident, and the rest of the team nodded along with Bucky.

“Fish can swim faster than we can,” Sam noted, then looked around the table. “Well, faster than I can. So we’ve got speed and stealth going for us.”

Romanoff shrugged. “Starfish don’t swim very fast.”

“True, but they have other… skills that could be useful. They can grow back limbs and digest coral in a really gross way.” Stark looked around, noticing the general surprise that he'd actually said something worth listening to. “What? I saw it on a documentary.”

“As long as the starfish can hitch a ride on the shark’s back to the sub. Five miles is a long way,” Romanoff said.

Steve put on his team-leader face. “So, it’s agreed, we give this thing a try.” He turned and looked at Bucky. “You said you’re feeling okay after all that, right?”

Bucky nodded.

“Story of his life.”

“Stark…” Fury growled.

“Then let’s get on it.” 

Steve stood up and the meeting was over.

<>< <>< <><

Seaweed and plankton drifted back and forth in the warm water around them. It was beautiful and soothing, until Bucky remembered why they were there. He couldn’t afford to lose sight of the mission. The sub hovered threateningly nearby in one direction, and a small, seemingly sparsely populated coral island rose from the seafloor in another.

At the moment, he and Steve were swimming in opposite directions in a large circle around _The Splasherator_ , Stark’s newly-christened bathysphere, their tails brushing briefly as they passed one another. Steve was now a large dolphin, which had surprised exactly no one.

Hill, Selvig, and Cho sat inside the craft, monitoring the location of the sub and the team. They also maintained contact with Simmons and Fury on the Helicarrier, which hovered several thousand feet above them, should its heavier firepower be needed. 

Bucky took a moment to note that the indigenous fish around him didn’t dash away as he’d expected they would around a predator. Perhaps they could sense he wasn’t hungry, or that he wasn’t a real shark. 

Then again, maybe they were just confused by all the inane chatter around them. 

“Romanoff, where’s Romanoff?” Stark clicked his lobster claws in agitation. He awkwardly backed up a foot, turned right, turned left, and peered into the gloomy depths with his stalk-like eyes. “I can’t see shit.”

“You’re standing on me.”

Stark skittered away as a flatfish shook sand off its back and surfaced in front of him from a mound of tiny pebbles. 

“Hill says you and Barton should make your way towards the sub. You’re our spies, time to get spying.”

Barton shot out a purple spine from his spherical mauve sea urchin body, which pinged ineffectually off Stark’s carapace. “Why us? You could just as easily walk up to that sub.”

“Not without a hundred other lobsters behind me. It'd look suspicious. Come on, man, this is what I’m talking about - don’t you ever watch nature programs?”

Steve adopted his Captain-America-is-done-with-your-shit voice, which was seriously at odds with his cheerful permanently smiling face. “We’re wasting time. Nat, Clint, we need recon. Get close to the sub and report back ASAP.” 

Barton spun around - or at least Bucky thought he did. There was no knowing which way a sea urchin's head was facing, so it was hard to tell. “Wow, Flipper got bossy.”

“Flipper?” Steve asked. 

Bucky sighed, clicking his razor-sharp teeth. “I’ll add it to the list.”

“Wait, when did the Winter Soldier have time for _Flipper_? Oh, I forgot you were around in the sixties; couple of high-profile missions, right?”

“Tony, shut up. Nat, Clint, get going,” Steve whistled in annoyance.

“Can’t I just eat him a little?” Bucky asked as they passed each other on their circuitous routes.

Steve ignored both of them and rose to the surface. Bucky heard his blowhole open and then watched as Steve jerked his head from side to side, probably scanning the horizon for Sam. 

“How’s the island evacuation going?” Steve said to the large shadow that settled above him. 

Beneath the shadow, Bucky saw huge webbed feet slowly paddle in circles to keep their owner stationary. He manfully - fishfully? - resisted the urge to tug on them with his teeth, just to be a dick.

A loud squawk came from above and Sam's voice sounded in his head. “It isn’t,” he said. “No one on the island thinks there’s anything to be worried about. Probably because no one believes a talking albatross.”

“MINE, MINE, MINE!” Stark’s shrill call rose from the murky water. 

“That’s a seagull, asshole,” Sam shot back. The feet above Bucky’s snout paddled more quickly in agitation.

“Watch the language, Jonathan Livingston.” Tony’s claws clicked through the comms. “Flipper doesn’t like it.”

“Just keep at it, Sam. We need to get those people to safety in case things go south.”

“Is that a bird joke?” Stark sounded almost impressed.

“Will do,” Sam said to Steve. The water churned above as the feet and the shadow disappeared from the surface.

“ALBATROSS, GET YOUR ALBATROSS HERE!”

“Stark, I’d fire you if I thought it would make you go away,” Fury’s voice cut through the roiling water. 

Bucky and Steve passed each other once again, just as a large snake-like fish joined their circuit. 

“I still do not understand this magic. But I like it.” Thor’s voice rumbled so loudly that Bucky feared it might be detected by the sub.

“It’s very simple, actually," said a near-transparent foot-long squid. "You’re turned into whatever form best suits you.” Having delivered this explanation, Banner squirted himself around above the bathysphere. "This is quite relaxing, all things considered."

“And how does this form suit me? I am not long and thin in my natural form.” Thor observed. 

“That’s for sure,” someone (Bucky could have sworn it was Cho) muttered.

“You’re basically yourself, Thor," Banner-squid went on. "Instead of wielding a hammer full of electricity, you’re carrying it around inside your body.” 

There was a pause and then, “MAGNIFICENT! So I just -”

The loud crackling of electricity that Thor had unwittingly emitted had them all jerking around and looking at each other, making sure they’d not all been electrocuted. All but one of them hadn’t been.

“Banner!? Banner? Are you all right, my friend? Sun’s getting real low...” 

“Nice work, Point Break.”

“I’m… good...” Banner's voice trailed off weakly as his tube-shaped, multi-legged body sank down to the roof of the bathysphere and lay there motionless.

"It’s okay, walk it off, you’ll be fine.”

“Walk? Tony, are you blind?” Barton sounded incredulous.

“Pretty much, yeah.” 

“He’s a squid," Barton said, "he’s not walking anywhere.”

Banner slowly raised his body and squirted erratically off the craft. “I’m fine, I’m fine. Just… just… only do that around people you don’t like from now on, okay Thor?”

“He means Zola’s goons, not just the people _here_ you don’t like.” Stark clarified.

Bucky rolled his eyes, an easy habit to get into as a shark. “Steve, are we sure no one can hear us?”

Hill responded, “We're good, Barnes. But that doesn’t mean you guys need to fill the comms with this shi-”

“We’re at the sub,” Barton interrupted. “There’s definitely movement inside.” 

“Audio link engaged,” Bucky heard Romanoff report. They must have attached the link to the sub. The plan had been to use very low-tech but highly efficient sea urchin slime for that. Which means they’d made it there without detection, exactly as hoped. “Sounds like there’s another EVA planned for tonight. Resupply with troops and provisions from the island. Sam, do you see anything from up there?”

“Nothing happening at the moment, but they could be waiting till it’s dark.”

Steve’s tail flicked up and down in a business-like manner as he issued orders. “Nat, Clint, stay hidden if you can, but keep the audio link operational. Our strike team can be there in minutes, but until then, we’ll hang back here. We don’t want to risk being seen on sonar, even in fish form -”

“Technically you’re not a fish.”

Hill got there first, “Stark, shut up.”

Steve sighed a long string of bubbles. Bucky amused himself by snapping at them.

<>< <>< <><

Sam’s voice broke the uncharacteristic silence half an hour later. “We have movement on the shore. Four inflatable dinghies being filled with cargo. No lights, lots of coded hand signals.”

Steve nodded his long nose toward the surface. “Thanks, Sam. Thor, Banner, assemble at my location. Nat, what’s the status?”

“Popping, sub going shallow,” Romanoff said.

“Wow, this is just like _Hunt for Red Oc_ -”

“SHUT UP, STARK!” Hill sounded near the end of her tether.

"What's _Hunt--"_

“It’s on the list.”

“ROGERS, BARNES, YOU TOO!” The end of the tether had officially been reached. "Go!"

Steve, Bucky, Thor, and Banner cruised toward the sub. The nautical scenery zoomed by, Steve in the lead, the others following in his literal wake. 

“Banner, don’t Hulk out till we’re ready to engage. I want us to look as harmless as possible.” Steve pulled up twenty feet from the sub, rose to the surface, and began swimming in playful circles, as any dolphin might, curious of this new thing. Bucky slowed and began leisurely stalking the fish swimming nearby. “Stark, you know what to do, but we also need you to make sure we’re not ambushed from the rear. Get yourself back to human form and into your suit.”

Sam’s voice cut through Steve’s instructions.”Cap, boats heading your way.”

“Understood.”

So far no one either on shore or on the sub seemed to suspect anything. Bucky noted some twisted and broken metal struts and realized that the "fishy" weapon he'd torn from the sub had not been replaced. Interesting. He wondered if that meant Zola hadn’t been able to reproduce the tech. Maybe the one he'd chomped off was the only existing prototype.

The team watched as a door on the upper curve of the port side of the sub opened with silent efficiency, and a ramp deployed and lay flat in the water to receive the boats. From where he was circling, Bucky saw that the interior of the loading bay was partially underwater.

Bucky held his breath, or whatever the shark-like equivalent of that was; he was so close, maybe too close. He felt all kinds of uncomfortable, but also a stolid resolve: he would finish Zola if it was the last thing he did, either in this body or his own. Never again would he allow himself to be manipulated by this monster - he’d come too far. 

He heard Steve whisper over the comms. “As soon as the crew comes out, we take them. Buck, you and Thor get the guys on the boats until Banner can bring out the warheads. I’ll take out the sub crew. Ready?”

“I’m going large,” Banner announced. 

Steve cautioned, “Remember not to crush the sub, Banner. Okay, everyone this is it. Go, go, go!” 

Men and supplies flew everywhere as Bucky and Thor took on the dinghies’ crews. They were like a two-man army, all sharp teeth and deadly electricity, and the sea quickly turned red. Bucky paused in his attack to watch as Steve swam into the hatch, his top half sticking out of the water as he navigated the ramp. Banner, now huge and a murky green color, wrapped his tentacles around either side of the hatch and launched himself into the sub. 

“Guys, there’s something happening inside,” Romanoff said. Clearly she still had ears - or something - on the sub’s comms.

Sam joined in, “We’ve got movement on the starboard side of the sub. Crew’s escaping out another hatch. They’re well-armed, so watch yourselves. Looks like some kind of alien tech, blue-”

“Yeah Sam, we’ve dealt with this kind of thing before. Buck, leave the dinghies to Thor, get to the other side of the sub, and see what’s happening. We don’t want them re-entering to intercept Banner,” Steve ordered. “I’ll deal with the ones still coming out here until I get in.”

Bucky slid smoothly under the sub, bared his teeth in his best horror-movie fashion, and managed to scare the crap out of the fleeing crew. He got in a few good chomps, and then reported back.

“Wilson’s right, Steve. It does seem like an army. They all have Hydra weapons and - SHIT!” Bucky quickly dodged a harpoon thrown from inside the flooded bay door. It sailed past and landed somewhere beneath him. “Watch out below, they’ve got harpoons as well as those guns.”

From the chaotic swirling of the water, Bucky guessed that Steve was bashing away crewmen right and left as he continued issuing orders. “We need to - ooof - get to Zola. If he fires those nukes - Banner, have you found them? I’ll go get Zola.”

“Steve!”

“Buck, I know you want to be the one to finally pull the plug on him, but I need you out here where you can get the crew with Thor. You’re much more efficient than I could be. Please? Leave this to Banner and me.” 

Bucky ground his teeth (and a couple of guns and the crewmen attached to them) in frustration, but he knew Steve was right. Banner had the delicate tentacles with which he could manipulate the weapons, and Steve had the sheer power to get rid of Zola for good.

“I’m in the weapons bay,” Banner said, his voice sounded hollow, like he was in a cavernous room. Which he probably was. “It’s pretty much what we thought. They’ve all got pretty sophisticated guidance systems, and look to have been modified with several kinds of functions I’m not familiar with. Oh…” 

“What is it, Banner?” Hill and Fury asked almost at the same time.

“He’s used gamma radiation in their manufacture. It’s affecting me and the weapons. I’m…”

“Banner!” Steve shouted. “Report! Do you need backup? I’m at the bridge but I could be there in-”

“I’m fine, Steve, but I’m…uh…even bigger now.”

“I bet you say that to all the sailors.”

“ **STARK**!”

Hill’s furious reprimand nearly deafened everyone, but Bucky had better things things to worry about than his hearing. More and more Hydra goons were crowding through both the port and starboard sides of the sub, now that Steve had gained entrance and was largely ignoring them in his quest to get to the bridge. Bucky was a good swimmer, and was great at biting the bad guys, but now there were just too many of them for him to take out himself. He began to feel the sting of harpoon tips, and even one or two painful blasts from the guns.

“I’m okay; Dr. Selvig and I anticipated, er, alterations like this. I’m still fine to start the defusing protocol." Banner’s voice echoed around them again. "I’m pretty sure my tentacles can function at this size.”

Fury growled very slowly and very ominously, “No. One. Say. Anything.” 

Steve saved them all by asking for sit reps.

“Lots of coded chatter on the comms,” Romanoff reported. “Can’t tell if it’s internal or if they’re signaling someone else. Clint’s moving in to stick himself to the side of the sub to get a clearer signal.”

“It looks like we're got about a hundred more submerged hostiles coming out on both port and starboard sides," Bucky called out. "Enhanced weapons, but I can deal with it." He didn’t want to burden Steve with his need for extra support, even if he was the team leader. Getting to Zola was more important. 

“Jesus, where were they keeping these people?” Clint asked.

Stark pounced. “I’m on it.”

“No, Tony, we need you to get those weapons safely from the weapons bay to Thor. Don’t deviate from the plan,” Steve admonished. In the background, Bucky could swear he heard eerie laughter emanating from somewhere. It was Zola, of course, in typical villain fashion, and Bucky thrashed around even more violently as his anxiety level rose. “I’ve reached the bridge.” Steve sounded crestfallen. “There’s no one here.”

“Is there a computer monitor still working?” Romanoff asked.

_“Ahhh, Captain Rogers, is that you? It must be! I see the weaponization of our latest 'donated' technology has been a success.”_

“It’s over, Zola. We’ve taken control of your ship and your weapons.” Steve sounded every inch his patriotic persona, but Bucky could also sense anger and disgust in his tone. “We’re done with you.”

“ _Once again, Captain, I see I must teach you a lesson. We will never be ‘done’. This endeavor has been merely...preparation. I am acquiring knowledge and building better armies at a faster rate than you can fight them. We shall meet again, of that I am -”_

A deafening crash sounded through the comms, and Zola’s tirade was blessedly cut off mid-sentence.

“Steve, what happened?” Bucky shouted..

“Accidentally bashed in the monitor with my tail,” Steve replied dryly. “Banner, I’m on my way to you. Buck, are you okay?”

“Not gonna lie, Steve, it’s getting hard to keep ‘em off me now.” Bucky’s shark skin, despite being nearly two inches thick, was taking a beating. The camouflaged sleeve on his fin had been torn away by blasts from the Hydra guns, and his tail was has been perforated by harpoons in several places. He gritted his teeth and bore it, though, in the process crushing a gun into smithereens.

“Gimme a minute, Buck, I’ll be there as soon as the weapons are gone. We’ve no idea if they’re timed or not. We can’t even be assured they won’t detonate while Banner is disabling them.”

“Steve,” Romanoff’s voice bubbled from the depths below. “Not helping.”

“What, you think he could get any bigger?” Tony asked facetiously.

“Just hang in there, Buck!” Steve said tensely. “Banner, I’m in the weapons bay. Pushing over a platform now.”

Banner’s surprisingly calm voice said, “I’ve got most of them deactivated. Tony, you can start moving them onto the platform now.” 

Wilson’s voice filtered in from above. “There’s a lot of reinforcement coming from shore now. I think there’s more Hydra soldiers than islanders there. More boats in the water too. Thor’s taking out as many of them as he can.”

Clint asked, “Should we let them go?

“No, regardless of Zola’s threats, we need to cut off this arm of Hydra here and now.” Steve had never sounded so sure of anything. Bucky was pleased to hear it.

“Romanoff," Hill cut in, "is there anything you and Barton can do from where you are? We can engage if necessary.”

“Don’t you dare dent my bathysphere!”

“I’m shooting out spines as fast as I can, but their wetsuits are too tough. Not sure if it’s helping. Barnes’ teeth are working fine, but there’s too many of them. Bad guys, I mean. And teeth, actually.” 

Just as Barton spoke, a new wave of scuba-suited henchmen emerged from a second portal that had whooshed open, and Bucky found himself completely outnumbered. He was either going to have to leave the entrance he’d been covering to deal with this, or risk someone doubling back to the weapons bay.

Before he could take action though, movement from underneath the sub caught his eye. At first he thought it might be Barton or Romanoff drifting upwards, but it was far too big to be either of them. And not just big… dense. 

It wasn’t an _it_. It was a _them._

Stark’s AI must have seen them too, and although Stark was now engaged in removing the warheads, he said, “We’ve got incoming, And I mean a lot of incoming. They’re swimming directly towards us.” 

"Confirmed," Fury said from the Helicarrier. “Friendlies?”

“Nat,” Bucky heard Steve ask, “what do you hear?

“Nothing on sub comms. I don’t think this is Hydra. I’ll move along the sub and keep checking.”

Hill reported, “We’ve got nothing on comms here, either. No one’s talking but us. Stark’s right, though. There’s something big headed directly for you.”

“It looks like an enormous school of fish,” Simmons gasped.

“It is," Bucky said. "Count about a hundred of them.”

Hill asked, “What kind of fish? Do they look dangerous?” 

Bucky responded, although he thought that was an odd question to ask a shark. “Lots of...fins. And kinda...spiky?” 

The massive shoal surrounded him in a sea of floaty, beautiful, but deadly-looking spines. The rush of fish beside him set the water churning, and Bucky found himself tossed and turned in the current they created.

“Barnes, what are the colors and markings?”

“Uh…”

Stark now sounded exasperated. “Anyone? Really? Fish documentaries are your friends, people.”

Wilson’s big feet appeared above Bucky’s head, though he could barely see them through the mass of fish. Sam’s long beak pierced the surface of the water, followed by his head. ”They’re lionfish. We had one in a tank when I was in high school. They’re predators, venomous, and invasive. They've turned up in some ocean areas in large numbers and killed off a lot of the indigenous species.”

“That’s what I’m talking about! The man knows his fish.” Tony said, clearly pleased with Wilson’s report.

Wilson continued, “These are… really big, though. And a different color than any I’ve seen. They’re black and…silver.”

Bucky added, “They’re completely ignoring us and don’t seem to be stopping for anything...hang on. Except the Hydra teams.” Bucky swam down below the shoal and Wilson hovered above, and they watched as the lionfish dealt with the majority of the sub’s remaining crew. 

“Barnes is right, they’re going for the crew. Steve,” Wilson observed. “I’d say we have some kind of fish army on our side.” 

“Then let’s take advantage of it and get moving. Sam, you, Nat, and Clint keep a close eye on those fish. They may be on our side or they may not, and we can’t afford to have them jeopardizing this part of the mission,” Steve instructed. “Hill, get some pictures of these nukes with the bathysphere camera when we come out, then get to cover. We may need your help if we can’t get clear of these fish, or if they make a play for us, so don’t get too far.”

“Understood,” Hill said, businesslike. 

As Bucky watched, Steve and Stark left the vessel pushing along a huge submersible pallet, on which sat a large array of missiles. 

Bucky saw the bathysphere lights flare as its underwater camera recorded the image. Then it turned and made its way towards the outcropping of coral closer to the island’s shoreline.

“I’ve got your six, Steve,” Bucky said, taking off towards the port side of the sub and the heavily-laden pallet. 

He saw that Banner had carefully draped himself over the now-deactivated warheads, steadying and securing them under his ten tentacles, as the pallet moved off the short metal ramp and into the water. Bucky joined them, and together they propelled it toward the large electric eel waiting for them some distance from the sub. 

All around them, Hydra sailors were slowly sinking to the ocean floor as the spiny fish made short work of them. Just as Bucky, Steve, and Stark rendezvoused with Thor, the synchronised school of fish all turned as one and entered the sub through the same doors the team had just exited.

There was no time to follow them and see what they were up to. Bucky stood sentry with Steve and Stark, as Banner squirted away from atop the missiles. Thor, sizzling like a downed power line, summoned the Bifrost. A huge rush of rainbow-colored plasma poured violently but beautifully through the surface of the water, hiding the weapons behind a shimmering curtain. When it faded, the pallet and all the weapons had disappeared.

As the roaring of water rushing in to fill the now-empty space faded, it was replaced with sounds of explosions. The sub was being scuttled. 

“SAM! REPORT!” Steve shouted, turning and darting towards the sub, his tail pounded up and down in the effort to reach it quickly. Bucky and Stark followed as fast as they could, though they couldn’t get too close without being caught in the explosions or trapped beneath chunks of metal as it fell to the ocean floor. They hovered anxiously, peering through the wreckage.

“We’re good,” Sam reported, and Bucky and Steve exchanged relieved glances. “Barton and Nat hitched a ride on the bathysphere, and we’re all within reach of the island now.”

“Status of the sub, Captain?" Fury called from above. "Is it salvagable?”

“I think it’s been salvaged already,” said Banner, as they watched the school of lionfish moving stacks of containers on inflatable pallets. “Those lionfish, they’re taking equipment - looks like computer components, engineering supplies -”

“Not the toilet seats!” Barton called.

"Roger that," Sam said, “They’re raising it all to the surface and coming this way.”

Thor, jubilant as always, seemed unconcerned over this new development. “Nothing left here but fish food. Ha ha ha!”

Romanoff’s voice filtered through, “Don’t suppose anyone found Zola.”

“Nothing more than the last time, Nat.” Steve sounded sullen. “Which means he’s still out there. Being blown up with this sub probably didn’t affect him any more than being blown up in that damned bunker.” Steve looked around at the team still beside him. “We shouldn’t overstay our welcome with these other fish around. Everyone make for the island. We’ll regroup there and get our human forms back.”

“We’ll be ready,” Bucky heard Simmons say.

Stark, using his thrusters, shot out of the water, and Banner shrank back into his non-Hulk size. Steve swam over to Bucky and touched the now-unconcealed fin with his own. 

Together they made their way to the island to rejoin their team and regain their humanity. 

<>< <>< <><

When the team - now bipedal and breathing air - returned to the Helicarrier, they found Cho and Fury in conversation with a tall regal-looking man, wearing a long black robe detailed in silver, and two women, one armed to the teeth and looking like she could take down all of them, the other wearing Converse sneakers and a hoodie with "Coachella" splashed across it.

“Avengers, meet General Okoye, Princess Shuri, and King T’challa of Wakanda.” Fury motioned to each as he introduced them. 

“Of course. The vibranium came from Wakanda.” Steve said.

“Yes, so naturally, they wanted it back,” Fury finished.

“Well,” Steve said, sizing up the newcomers just as they were being sized up themselves. “They’re going to have some trouble getting it back.”

“On the contrary,” said T’challa. His strongly-accented voice was calm. “We have come to thank you for retrieving it, as well as retrieving our other stolen technology. We saw that you had used it admirably and fought bravely.”

“Wait a minute…” said Simmons. “ _You_ developed the fish-ray-thingy?”

“Well, technically _I_ did,” said Shuri with a bright smile. “And it’s called a _Stingray_.” 

T’challa shook his head with a patient smile. 

“Of course it is!” Stark interjected. “Whoever you are, come with me.” Without a backward glance, he steered Shuri over to a console covered with computer equipment. 

T’challa turned back to the rest of the group. “It did not start out as a weapon, and technically it isn’t. It was made to use on plants and animals not indigenous to Wakanda, to enable them to grow and thrive unaided. I do not know how it became this…stingray. I’m not sure now why we still need it.”

“Because we just do!” Shuri called loudly from the other side of the room.

T’challa grinned. He had a warm smile, but Bucky’s heightened senses kept him at the ready, regardless. Steve looked calm, standing at parade rest, but Bucky knew he felt the same.

“I trust it did not affect anyone unfavorably? Shuri was unable to coerce me into testing it, but I believe Okoye spent an hour as a narwhal before we were able to change her into the lionfish Shuri had been attempting to create.”

Barton pointed at Okoye. “ _You_ were a lionfish?”

“Yes, I and my Dora Milaje, as well as much of T’challa’s army.”

“A magnificent display of battle skill,” Thor said admiringly.

Cho blinked at T’challa and Okoye. “I would like to understand how you were able to achieve a single-species conversion. The genetic manipulation must have been profound.”

“You’ll have to ask my sister.” T'challa cocked his head in Shuri’s direction. She’s the engineer, geneticists, and ichthyologist. I am but a simple king.”

“Simple is right,” Shuri called from the console. “Tell me, did it match each of you to your perfect aquatic counterpart?”

“It turned Cap into what’s effectively the golden retriever of marine life, so yeah, it worked on him just great. I should have been something more bad-ass than a lobster, though,” Stark complained, “I say, let’s make this thing even better.”

Shuri nodded and they high-fived.

“Mr. Stark’s reputation precedes him. Shuri has been a fan since she was three,” T’challa explained.

Selvig strode into the room with his head buried in a sheaf of papers, and nearly ran right into T’challa, who easily glided out of his path. He looked up at the king with a quick, “Oh, sorry,” before walking over to stand between Steve and Banner. “Look at these.” He held up the grainy photos of the warheads that Stark had snapped from the bathysphere. “Do you think that the missiles' multi-directional function with vibranium enhancements would continue to be operational even when deactivated?”

Bruce looked thoughtful for a long moment before responding. “The targeting readouts were still nominal when I shut down the drives and weapons system. But they’d all been reset, so no target coordinates were -”

“Did you just say _drives_?” Cho asked. Everyone but Stark and Shuri turned towards her.

“Uh…yes?” Banner blinked at her.

“Captain, you said Zola had linked his digital self into a computer mainframe several years ago, yes?”

Steve nodded but said nothing. All eyes were now on Cho.

“And this time he communicated via the operating system installed on the submarine?”

Again Steve nodded. Banner shuffled his feet and looked from her to Selvig. Cho turned to him too.

“And these weapons possessed vibranium-enhanced SMART memory systems, which you wiped when rendering them inert?”

Bucky was no scientist, but even knew that Barton was forever deleting things off his phone because his favourite gaming apps took up too much space.

Thor cut into Bucky’s musings. “You have said the weapons cannot be detonated, and Heimdall will have sent them far beyond the Nine Realms by now. There are many desolate and empty systems between here and Heigentar; you may rest assured they will harm no one.”

“It’s not the weapons we’re worried about,” Selvig said, seeing Steve’s frown. “When the missiles’ targeting and other functional data were removed, there would have been a huge amount of empty space - so to speak - left in their drives.”

Romanoff spelled it out for everyone. “Zola could have downloaded himself into any of them.”

“Or...all of them,” Selvig clarified. 

“But without anything to…do…with himself wherever they ended up, could he pose a threat? Wouldn’t he just be stuck in a non-functioning machine on an empty planet?” Simmons asked. 

“Unknown,” said Cho. “The studies Bruce, Tony, and I have begun show that sentient AI or machine-based consciousness can be made manifest, but we’re still in the early stages of our work. It’s unlikely he could do anything alone.”

There was a moment of uncomfortable silence.

“Well, I feel better already,” said Stark, rubbing his hands together, “Who wants sushi for lunch?”

The End

**Author's Note:**

>  _Ongwe_ means “big cat” in Kwanyama - which, I’m reliably informed, is the language most widely spoken in Namibia, aside from English. Apologies if I’m wrong, and please correct me.
> 
> The Heigentar system contains both the Kree homeworld and the planet Vormir.


End file.
